A Merger With Upside For Both Companies

The expected purchase of Wall Street up-and-comer Jefferies by low-key Leucadia National looks like a good move for both companies.

Leucadia National Corp.'s surprise deal to buy Jefferies Group for $3.5 billion in stock marries a secretive company that resembles a small-scale Berkshire Hathaway to a scrappy financial-services firm that has the best stock-market performance in the industry since 2000.

The transaction, which likely will gain shareholder approval, looks like a good deal for both companies. It will give Jefferies a larger capital base and access to...